This invention relates to an apparatus for manufacturing dual component fibers from thermoplastic materials and, more particularly, to a spinner apparatus for centrifuging dual component fibers from two streams of molten thermoplastic materials such as glass or other mineral fibers or polymer fibers.
Fibers of glass and other thermoplastic materials are useful in a variety of applications including acoustical or thermal insulation materials. Common prior art methods for producing glass fiber insulation products involve producing glass fibers from a rotary process. A single molten glass composition is forced through the orifices in the outer wall of a centrifuge commonly known as a spinner, producing primarily short, straight glass fibers.
A modification of conventional glass fibers, which are usually straight fibers, is the use of fibers which are curly (helical) in shape. These fibers can be made by joining two distinct glass streams, commonly referred to as A glass and B glass streams, and centrifuging the dual glass streams into a curly (helical) fiber.
Stalego, U.S. Pat. No. 2,998,620, discloses curly (helical) glass fibers of bicomponent glass compositions. Stalego discloses producing staple curly fibers by passing two glass compositions having differing coefficients of thermal expansion through the orifices of a spinner. The glasses are extruded as a dual glass stream in aligned integral relationship such that the fibers curl naturally upon cooling due to the differences in their coefficients of thermal expansion. Stalego discloses in one embodiment a spinner having two vertically spaced distributing surfaces. The first distributing surface is defined by the bottom of the spinner. It receives one stream of molten glass. A distributing table surface is mounted a vertical distance from the first surface and defines the second distributing surface. The table surface is mounted such that its circumferential edge bisects each of a plurality of orifices so that glass on each level is ejected by centrifugal force through only half of each orifice. Thus, the glass on the two distributing surfaces flow together at the orifices and are emitted as bi-glass streams to be attenuated into fibers.
However, there remains a need in this art for improving the delivery of dual streams of molten glasses to form dual glass or other thermoplastic fibers.